So here's my consensus on OEM boards:
HP
SK-2885 - horrible.
KB-0316 - mediocre to pretty bad, leaning towards bad.
Lenovo
SK-xxxx - basically, the black one with the blue enter - mediocre to horrible.
Dell:
RT7D5JTW - Very, very good. One of the best rubber dome boards out there.
SK-8000 - okay to mediocre. Much worse than RT7D5JTW, but still okay. Keys wobble; feel is okay.
SK-8115 - not that bad when new; key feel is really good and nice and light, but the board is featherweight and the extended keys lack stabilizers except for spacebar and right sfhit. Probably terrible when old; the keys are going to bind.
L100 (identical aesthetically to SK-8115) - horrible, SK-8115 with worse feel, same cheaped out stabilization, and much better keys. They're still probably going to bind.
RT7D50 (identical looks wise to earlier two) - probably the better of the bunch, though the stabilization is still cheaped out and it's going to bind over age.
SK-8125 - feel is wonderful; no stabilization over longer keys except space and shift, though tolerances are tighter than SK-8115 and it's more tolerable; those keys probably binds over age.
KB-1421 - Excellent. Likely metal backplate judging by weight, and the key feel is very good. Excellent stabilization across all keys it seems.